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Messages - joecool85

#1
Quote from: saturated on February 02, 2025, 05:43:03 AMAbout forty years ago when I was still in college and working part time the university had afternoon/evening classes I guess it was geared towards working older people  xP

So anyway I was a 🦇 vampire staying up all night doing homework and playing guitar 🎸 etc and my routine had me going to bed 🛏� at about 0530.  I had found that Casper the friendly ghost 👻 came on like at 0500 and that was my SOP.

So what does all that have to do with anything?  :loco
At night in the small town it got quiet with the exception of an audible hum  :grr
Sometimes I would have the windows open I was in an upstairs room at the end of the house.  This (real or perceived) hum/pitch/monotone frequency tormented me to some end.  In fact I made a few nocturnal excursions around town looking for it.  I would drive around to different areas and shut the engine (slant six 66 Dart) off and sit and try to determine where it was coming from.
Spoiler alert: I never did find it or find out anything.
When I told my dad about it he said there was a composer that went crazy because of constantly hearing 440 or something  :trouble

xP

Was there a hydro-electric power plant nearby at all?  Or did the college have a steam plant?  They create hum like you are describing.  UMaine Orono has a steam plant, and a lot of northern colleges do.  Not sure about out your way.
#2
Quote from: blackcorvo on February 01, 2025, 06:17:58 PM
Quote from: joecool85 on February 01, 2025, 04:38:33 PMI think this sounds awesome!  Great job!

What is the signal chain though?  IE - is the guitar going straight into the cassette adapter or is there a preamp or pedal first?  Any added distortion circuitry?

The chain is:
Guitar>headphone amp>cassette adapter in recorder>out (cabinet or p.a.).

On the first video, there's a couple parts of the first clip where I lower the volume of the recorder and you can hear most of the distortion get dialed back. It basically adds crunch on top of whatever you're using to push the recorder.

[EDIT]
And for anyone curious, the schematic for these recorders is freely available on Elektrotanya: https://elektrotanya.com/sony_tcm-s63_s64v_s65_s66v.pdf/download.html

What are you using for headphone amps?  Are these Vox amPlugs?
#3
Quote from: Tassieviking on January 30, 2025, 10:47:14 AMI just cheat and find a calculator on the net. :)
...
http://sim.okawa-denshi.jp/en/Fkeisan.htm

This is the one that I use!
#4
I think this sounds awesome!  Great job!

What is the signal chain though?  IE - is the guitar going straight into the cassette adapter or is there a preamp or pedal first?  Any added distortion circuitry?
#5
Quote from: argenta on January 14, 2025, 10:06:11 PMHappy New Year all. I did indeed replace the power transistors and the driver ones as well. With the power transistors, I made sure they are insulated from the chassis, however, when testing for shorts between the transistors and the heat sink I observe the following:
The meter reads short circuit initially, then over a few seconds resistance increases to open. Why is that?

Have you built a lightbulb limiter yet like Phil mentioned?  https://www.ssguitar.com/index.php?topic=2093.0

If you need one, PM me.  I have one collecting dust that I'd be glad to send your way if you pay shipping.
#6
Quote from: megatrav on January 08, 2025, 09:27:37 PMI think a single LM3886 chip amp at 50-ish watts would be plenty for a guitar amp.
Especially if it's going through a 2x12 or 4x12

I think it would be better to use class d for bass amps.

If the TI chips can't really achieve their listed wattage, I bet the ICEPower modules can.

There are other options too.

I had no issue getting an easy 50w out of my LM3886 when I built mine.  And even with a Dean Markley 10" PA cab, it was loud enough to bother the neighbors...

I don't think people realize how loud 50w can be into a proper speaker.
#7
I have compiled all the LM1875 and LM3886 files here: https://www.ssguitar.com/index.php?topic=5506.0
#8
Thanks to analogclassics.com, I found the manual for the LM3886!
#9
Schematics and Layouts / Chipamp.com LM3886 and LM1875
January 08, 2025, 06:33:21 PM
Chipamp.com used to be "the place" to get chip amp boards.  They have since gone out of business though, but Brian Bell (aka BrianGT) has provided Gerber files for the LM1875 and LM3886 amp boards as well as the excellent snubber PSU board designed for powering up to two LM3886.  And I found the old LM1875 manual from when I helped him test it.
#10
Quote from: J M Fahey on January 01, 2025, 02:31:17 PMHAPPY to see Mouser now has them in stock, in large amounts.

It was not so for *years* , where they did not straight say "forget it" but gave ridiculous lead times for restocking.

Oh well, all is well that ends well.

In this case, it becomes again an option for a Guitar amp.

Personally much prefer the metal tab version

A slice of mica or a laminated silpad or even Mylar insulator will *always* be thinner (so better heat conducting) that some Epoxy or any other plastic that has to be *injected* into a die, and flow to fill it.

The OP can use that KT something board or any other tried and proven one.

There is a guy at DIY Audio called "Brian GT" who has been supplying high quality LM3886 boards for years now, hundreds have been built by Forum Members with success.

I thought Brian got out of the chipamp biz?  He used to run chipamp.com and had great LM3886 and LM1875 kits.  I actually helped him test the LM1875 kits back when I was in college.  Last I knew, he had sold chipamp.com maybe 10ish years ago.

**edit**
Yup: https://www.diyaudio.com/community/threads/my-first-try-at-a-lm3886-layout-any-comments-suggestions.49813/page-15#post-5147555

According to this post from Brian in 2017, he had sold chipamp.com to a friend and it went downhill.  In this thread he provides the gerber files if people want to print their own LM3886 and LM1875 boards though - which is awesome!
#11
Nicely done!  Looks very professional.  8)
#12
Tubes and Hybrids / Re: Another standby switch thread
January 08, 2025, 06:16:33 PM
Quote from: Miyagi_83 on January 06, 2025, 04:03:45 PM
Quote from: saturated on January 06, 2025, 12:49:49 PMThanks guys last night I gave it a work out.  When I changed pedals I put it on standby.
When changing pedals there's no need to put your amp on standby. Just pull the cable out of your amp's input jack, disconnect and connect whatever pedals you want, and put the plug back in. Or simply turn the gain knob all the way down and then reconfigure your pedal string.

I feel like hitting the standby my be the quickest option regardless though, and it does no harm.  But your option is fine as well.
#13
The Newcomer's Forum / Re: Newbz and DC power supplies
December 29, 2024, 10:59:37 AM
Quote from: phatt on December 29, 2024, 07:16:06 AMYou got it, also I'd add that keep Main wires Separate from Secondary wires for extra safety. I've seen a lot of Big name brands tie Primary & Secondary in a bundle and it's not allowed in Military and Medical electronic Equipment for the obvious reason that if there is a Catastrophic failure it could connect mains to YOU which obviously would not go down well in a hospital. :trouble   

100% agree.  I forgot to mention in this thread, but I bring it up all the time - make sure to NOT put any mains lines on a PCB shared with anything else!  I can't stand it when I see electronics like this.  It's just asking for an issue.
#14
Quote from: J M Fahey on December 29, 2024, 10:06:39 AMIf you want the hands on build challenge, fine with me, just get the Velleman board, either as a kit or on its own, use your own heatsink and transformer.

I agree, if you want to do this circuit or similar, the Velleman kit is the best premade option.  Alternatively, you could create your own board in Kicad or similar, and get it printed through one of the various online PCB retailers.  I use OSHPark.com typically.
#15
The Newcomer's Forum / Re: Newbz and DC power supplies
December 19, 2024, 11:18:18 AM
Quote from: phatt on December 18, 2024, 08:08:54 PMI personally like to put the Fuse First but up to you.
Phil.

100%  Always put the fuse as the first thing inline with the power input.  That way if there is an issue with the switch, or anything after the switch, the fuse will take the heat.